Technical Field
The present invention relates to an image forming lens and an image capturing device.
Description of the Related Art
A so-called “industrial camera” is widely put into practical use, and for example, an image input device for machine vision, etc. are developed.
For an image forming lens used in the image input device for machine vision, it is important to have stable lens performance that is little varied due to focusing.
There is a known technology disclosed in JP-2013-218015-A as an optical system in which lens performance is suppressed from being varied due to focusing.
The optical system (lens system) disclosed in JP-2013-218015-A includes a first lens unit having positive refractive power and a second lens unit having positive or negative refractive power.
Further, the first lens unit is formed by sequentially arranging, from an object side to an image side, a lens unit 1a having positive refractive power, an aperture stop, and a lens unit 1b having positive refractive power, and focusing is performed from an infinite distance object to a short distance object by moving the first lens unit to the object side.